Severe Allergic Contact Dermatitis From Octylisothiazolinone in Over-Ear Headphones: A Case Series

Octylisothiazolinone (OIT; CAS 26530-20-1) is used as a biocide in leather products. To report several cases of allergic contact dermatitis (ACD) from the use of headphones containing OIT, and to highlight the strong allergic potential of this preservative. Four patients with ACD from headphones were patched tested using the European baseline, cosmetic, rubber, plastics/glues and acrylates series. Patients were also tested to different parts of their own headphones ('as is'). Chemical analyses of the headphones was additionally performed with Ultra Performance Liquid Chromatography-tandem mass spectrometry (UPLC-MS/MS). All patients had developed localised ACD to the contact sites of the headphones, except for one patient who developed 'angioedema-like' dermatitis. All patients were shown to have been primarily sensitised to OIT. UPLC-MS/MS analysis confirmed OIT in the leather ear pads of the headphones. OIT is a relevant and strong sensitizer in leather, and may cause severe ACD. Safer use concentrations (limits) of OIT, as well as product labelling in the leather industry, may be required to ensure a better protection of consumers.